Graduate Theses & Dissertations

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Thinking High When Feeling Shy
Social anxiety often co-occurs with substance use disorders – various psychological variables, contextual factors, and implicit cognitions may help explain their relationship. This thesis examined whether social anxiety and psychological variables (jointly and independently) helped predict substance use and related problems. It also explored whether social anxiety group membership helped predict implicit cannabis-sedation associations and substance use desirability. A sample of undergraduate student volunteers (N = 65) completed a computer task, questionnaires with anxiety-provoking vignettes, and online questionnaires. Results indicate that fear of negative evaluation and anxiety sensitivity are important predictors of alcohol and cannabis (respectively) use and problems. Social anxiety group was related to increased cannabis desirability in performance contexts. No significant implicit cannabis-sedation associations were identified. Our findings highlight the importance of certain variables in social anxiety and substance use relationships, and considering contextual factors when assessing substance desirability. It also provides preliminary evidence of a novel implicit cannabis-sedation measure. Author Keywords: Coping, Emotion, Implicit Cognition, Social Anxiety, Substance Use
This Is It, I Guess
Queer youth are an at-risk group, with an incredibly high rate of harm and death as they grow into themselves. They are often advised to wait until they finish school to express their sexuality more openly, when they can leave to somewhere that is “better”, which in this context can mean safer, more accepting, or far away from friends and family who may reject them. Unfortunately, much of the media representation of queer people is regressive or stereotypical, usually involving the suffering or death of its queer-identified characters. It is telling that a recurring theme in queer stories is that empathy and understanding for queer people can only be attained through their suffering. Non-queer people do not have to suffer to be understood. In this thesis I discuss the potential of creativity in academic works, I examine queer stories that buck the trend of tragedy through queer and pop culture theory, and I write a queer young adult novel in response, featuring a self-actualized protagonist whose sexuality does not cause him pain or trauma. Author Keywords: creative writing, queer literature, queer protagonist, queer theory, queer youth, young adult literature
Time Series Algorithms in Machine Learning - A Graph Approach to Multivariate Forecasting
Forecasting future values of time series has long been a field with many and varied applications, from climate and weather forecasting to stock prediction and economic planning to the control of industrial processes. Many of these problems involve not only a single time series but many simultaneous series which may influence each other. This thesis provides methods based on machine learning of handling such problems. We first consider single time series with both single and multiple features. We review the algorithms and unique challenges involved in applying machine learning to time series. Many machine learning algorithms when used for regression are designed to produce a single output value for each timestamp of interest with no measure of confidence; however, evaluating the uncertainty of the predictions is an important component for practical forecasting. We therefore discuss methods of constructing uncertainty estimates in the form of prediction intervals for each prediction. Stability over long time horizons is also a concern for these algorithms as recursion is a common method used to generate predictions over long time intervals. To address this, we present methods of maintaining stability in the forecast even over large time horizons. These methods are applied to an electricity forecasting problem where we demonstrate the effectiveness for support vector machines, neural networks and gradient boosted trees. We next consider spatiotemporal problems, which consist of multiple interlinked time series, each of which may contain multiple features. We represent these problems using graphs, allowing us to learn relationships using graph neural networks. Existing methods of doing this generally make use of separate time and spatial (graph) layers, or simply replace operations in temporal layers with graph operations. We show that these approaches have difficulty learning relationships that contain time lags of several time steps. To address this, we propose a new layer inspired by the long-short term memory (LSTM) recurrent neural network which adds a distinct memory state dedicated to learning graph relationships while keeping the original memory state. This allows the model to consider temporally distant events at other nodes without affecting its ability to model long-term relationships at a single node. We show that this model is capable of learning the long-term patterns that existing models struggle with. We then apply this model to a number of real-world bike-share and traffic datasets where we observe improved performance when compared to other models with similar numbers of parameters. Author Keywords: forecasting, graph neural network, LSTM, machine learning, neural network, time series
Time to adapt
To better understand species’ resilience to climate change and implement solutions, we must conserve environments that maintain standing adaptive genetic variation and the potential generation of new beneficial alleles. Coding trinucleotide repeats (cTNRs) providing high-pace adaptive capabilities via high rates of mutation are ideal targets for mitigating the decline of species at risk by characterizing adaptively significant populations. Ultimately, adaptive genetic information will inform the protection of biological diversity below the species level (i.e., “Evolutionarily Significant Units” or “ESUs”). This dissertation investigates cTNRs within candidate genes to determine their prevalence and influence under selection in North American mammals. First, I evaluated the potential for somatic mosaicism in Canada lynx (Lynx canadensis), and found that tissue-specific mosaicism does not confound cTNR genotyping success in lynx. Second, I assessed a selection of clock gene cTNRs across characterized mammals and found that these repeats are abundant and highly variable in length and purity. I also identified preliminary signatures of selection in 3 clock gene cTNRs in 3 pairs of congeneric North American mammal species, highlighting the importance of cTNRs for understanding the evolution and adaptation of wild populations. I further evaluated the influence of selection on the NR1D1 cTNR within Canada lynx sampled across Canada using environmental correlation, where I estimated the variation in NR1D1 cTNR alleles explained by environmental and spatial variables after removing the effects of neutral population structure. Although most variation was explained by neutral structure, environment and spatial patterns in eastern lynx populations significantly explained some of the variation in NR1D1 alleles. To examine the role of island populations in the generation and distribution of adaptive genetic variation, I used 14 neutral microsatellites and a dinucleotide repeat within a gene linked to mammalian body size, IGF-1, and found that both genetic drift and natural selection influence the observed genetic diversity of insular lynx. Finally, I estimated the divergence dates of peripheral lynx populations and made recommendations towards the conservation of Canada lynx; high levels of genetic differentiation coupled with post-glacial colonization histories and patterns of divergence at cTNR loci suggest at least 4 ESUs for Canada lynx across their range. Author Keywords: adaptation, Canada lynx, candidate genes, coding trinucleotide repeats, evolution, natural selection
Time, Being, and the Image
The three projects that make up this dissertation try to articulate an ontological idea of art; which is to say, they all approach art, or the imagination (as in project two), from the standpoint of a philosophical question concerning the sense of being. The ontological question is elaborated in terms of a theory of the spatial-temporal structure of the aesthetic or sensible realm. This kind of ontology contrasts with a more traditional metaphysical one, where the sense of being is sought within the purely intelligible realm, a realm that transcends the sensible. In projects one and two, the contrast is developed in terms of the Nietzschean/Heideggerian critique of metaphysics, and through the work of Jean-Luc Nancy, who appropriates this critique. In project three, it is developed in terms of Bergson and Deleuze’s critique of objective time, or of any attempt to define being and time in terms of what is static and unchanging. Art is central for the ontology at stake here, and the ontology is one of art, because it is a matter of questioning the spatial-temporal being of the sensible, and not the being of the purely intelligible; and because art (as I try to show) is itself essentially concerned with revealing this ontological dimension of the sensible. Author Keywords: Aesthetics, Art, Being, Fragment, Image, Time
Time-dependent effects of predation risk on stressor reactivity and growth in developing larval anurans (Lithobates pipiens)
The predator vs. prey dynamic is an omnipresent factor in ecological systems that may drive changes in life history patterns in prey animals through behavioural, morphological, and physiological changes. Predation risk can have profound effects on the life history events of an animal, and is influenced by the neuroendocrine stress response. Activation of the hypothalamic-pituitary-adrenal/interrenal axis, and the induction of stress hormones (e.g., corticosterone (CORT)) have been shown to mediate the onset of inducible anti-predator defensive traits including increased tail-depth, and reduced activity. The predator-prey relationship between dragonfly nymphs and tadpoles can be a powerful model system for understanding mechanisms that facilitate changes in the stress response in accordance with altered severity of risk. It has been well demonstrated early in tadpole ontogeny that increased corticosterone (CORT) levels, observed within three weeks of predator exposure, are correlated with increased tail depth morphology. However, the reactivity of the stress response in relation to the growth modulation in developing prey has yet to be fully explored. Accordingly, this thesis assessed the stress and growth response processes in tadpoles that were continuously exposed to perceived predation risk later in ontogeny. Continuous exposure of prey to predation risk for three weeks significantly increased CORT levels, and tail depth. However, tadpoles exposed to six weeks of predation risk acclimated to the presence of the predator, which was observed as a significant reduction of stressor-induced CORT levels. In addition, although increased tail depth has been attributed to predator defense, predator-naïve tadpoles began to display similar tail depth morphology as treated tadpoles at the six week time point. Thus, this thesis suggests that the stress response in lower vertebrate systems (e.g., tadpoles) may operate in a similarly complex manner to that observed in higher vertebrates (e.g., rats), for which severity of risk associated with the stressor aids in defining activity of the stress response. Moreover, the lack of morphological difference between treatments among tadpoles exposed later in ontogeny suggests that the mechanisms for inducing defenses are normal morphological traits in the development of the animal. This thesis paves the way for future research to elucidate the relationship between the neuroendocrine stress response and hormonal pathways involved in growth modulation in the presence of environmental pressures. Author Keywords: Acclimation, Corticosterone, Growth Modulation, Predation Risk, R. pipiens, Tadpole
To Sext or Not to Sext
The risks and benefits of sexting within an intimate relationship were explored. The present study focused on sexual gratification, relationship benefits, and sexual communication as benefits and risky sexual behaviour, unethical forwarding, and infidelity as risks. A cross-sectional online survey of both undergraduate students and a community sample was used. Results indicated that sexual gratification, relationship benefits (sexual and relationship satisfaction, relationship quality, and commitment), and sexual communication are related to sexting. It appears that risky sexual behaviour is not associated with sexting, instead those who sext frequently engage in more safer sex behaviours than those who sext infrequently. Unethical forwarding does not appear to happen very often in the context of intimate relationships. Lastly, the current research indicates that some participants are sexting secondary partners, and many consider sexting secondary partners infidelity. These results show that there are both risks and benefits of sexting, which can be used to develop sext education and therapeutic programs. Author Keywords: infidelity, relationship benefits, Sexting, sexual behaviour, sexual communication, sexual gratification
Tool-use and near-tool effects
After active tool-use visual stimuli near a tool are processed more quickly and accurately than those farther away from a tool. Can these near-tool effects be modulated by training demands? To investigate this we asked the participants to complete a tool training task followed by a cross-modal interference task. During the training task the participants performed quick and accurate pointing movements to reach a strict or moderate criterion. The results indicated that the strict group made faster movements than the moderate group. During the cross-modal interference task visual distractors were presented along handheld tools in conjunction with vibrotactile stimuli on the hand. No significant compatibility effects were found for visual distractors near the hand or tool tip, and no consistent group differences were found. Our findings demonstrate the importance of using a novel tool during training, and that virtual stimuli may not be effective to elicit near-tool effects. Author Keywords: bimodal neurons, cross-modal interference, near-tool effects, tool training, training demands
Towards a Critical Pedagogy of Globality
In this thesis, I use “Trump’s Wall” between Mexico and the US to resist Eurocentrism and the challenges Eurocentric pedagogy poses to the research-practitioner. In my method, I reimagine C. Alejandra Elenes’ borderlands theory as a zone of empowerment within a multicultural Canadian classroom, and braid it in a hybrid assemblage with the rhizome. The “rhizo-borderlands” assemblage uses selected field notes gleaned from my teaching practice to develop themes of a critical pedagogy of globality in personal, local and international dimensions. These are further braided with a “day-in-the-life” narrative of a fictionalized student (Ellie) who navigates her way towards a world literature classroom where the focus is The Kite Runner by Khaled Hosseini. This assemblage affirms my belief that teaching and learning provides a context where students become “border crossers” and navigate points of intersection between their local and global selves, in order to develop intercultural competencies. Author Keywords: Action Narrative, Critical Pedagogy, Rhizomes
Trace Metal Geochemistry in Peatlands
Peatlands can be found widely across all latitudes and play a significant role in global cycles within the earth’s biosphere. The anoxic conditions in peatlands promotes the accumulation of organic matter through decreased rates of decomposition and the storage of certain elements, which have received contaminant loading over the course of human existence, with significant increases occurring during the period of industrialization. We assessed global patterns of metal enrichment in peatlands in 439 cores distributed across 5 continents and 21 countries and measured 35 elements by depth increments and by peatland type. Global patterns in enrichment factors (EF’s) were determined for all metals with the majority of metals being found to have a median EF < 2 indicating relatively minor enrichment. Principal component analysis indicated EF’s of 6 metals (Cd, Co, Cu, Ni, Pb, and Zn), 2 metalloids (As and Sb) and Se in the upper peat horizon had similar spatial patterns among peatlands and these elements had generally the highest EF’s with many cores exceeding EF >10 and some having EF values >100. Significant differences in EF’s were found for these 9 “pollution” elements by peatland type and to a greater extent by geographic region, with higher EF values typically occurring in Europe and North America. Enrichment factors for most elements exhibited weak but significant positive correlations with modelled [1850 – present] S deposition. Estimated pools for the “pollution metals” within the 0 - 40 cm depth varied considerably, with median global pools in peat ranging from 12.9 mg m-2 (Sb) to 439 mg m-2 (Zn) for these 9 metals. Climate changes presents a significant risk to global peatland geochemistry due to expected changes in hydrologic regimes, resulting in potentially increased metal mobility though drought-induced peatland acidification, with historic areas previously impacted by industrial activities presenting the greatest risk of metal release to downstream receiving environments. Using a case study, we examined the impact of simulated 30-day drought on pore water chemistry at six sites in a peatland complex in Elliot Lake Ontario that were historically impacted by uranium (U) mining activities. All sites responded similarly to simulated drought with pore water pH significantly declining. The decline in pore water pH was likely due to increasing sulphate (SO42-) concentrations, which accompanied large increases in Al, Ni, Cu, Pb, Zn, and U. Dissolved organic carbon (DOC) increased, which may further enhance Al, Cu, and U mobility as these metals are strongly complexed by organic acids. Metal partitioning (Kd) values could be significantly predicted by pH and DOC although the strength of the relationship varied considerably among sites. Multiple linear regression and the inclusion of SO4-2 improved predictions, indicating that declines in pH as a result of SO4-2 and H+ production primarily governs metals and U partitioning in peatland soils. The results from both studies show that metal enrichment in global peatlands is highly variable, with northern peatlands in industrialized areas presenting the greatest risk of metal release to downstream surface waters based on expected hydrologic impacts from climate change due to historical and on-going metal and S deposition. Author Keywords: Acidification, Climate Change, Drought, Enrichment Factors, Global, Peatlands
Tracking Mercury and Mercury Stable Isotopes Throughout the Wabigoon/English River System
In the Wabigoon/English River system, mercury concentrations downstream from Dryden, ON, where there was a former chlor-alkali plant, remain elevated in sediments and biota. Understanding the current extent and severity of mercury contamination downstream from the former chlor-alkali plant is of great interest in furthering the clean-up of mercury within the traditional territory of Asubpeeschoseewagong Netum (Grassy Narrows) First Nation. The objective of this study was to evaluate the current level and extent of mercury contamination within sediments, crayfish, Hexagenia mayflies, yellow perch, spottail shiner and walleye in the Wabigoon/English River system. An additional objective was to use mercury stable isotope analysis to distinguish between legacy mercury from the former chlor-alkali plant and mercury from geogenic sources. Mercury contamination within surface sediments and biota at locations as far as 178 kms downstream of the historical source of mercury contamination are elevated relative to the reference lake, Wabigoon Lake. Isotope ratios in young of the year fish and sediments collected from within the system were distinct from fish from the reference lake, Wabigoon Lake, indicating that anthropogenic mercury contamination is distinguishable from geogenic mercury. Author Keywords:
Transcendental Turn
This dissertation traces the concept of transcendentalism from Kant's Critique of Pure Reason (1781) to Michel Foucault's historical a priori and Pierre Bourdieu's field and habitus, with implicit reference to Deleuze's `transcendental empiricism,' and the influence this trajectory has had on contemporary theory and culture. This general conceptual framework is used as the basis for a critical analysis of a series of examples taken from popular culture to highlight their transcendental conditions of possibility and the influence this conceptual paradigm has had on today's theory. The examples include the NFL `concussion crisis,' South Park's problematization of the discourse surrounding it, as well as the literature of Charles Bukowski, as an exemplification of an immanent writer-written situation. It is further suggested that, not only is transcendentalism an epistemological framework for thought, but it also doubles as an ontological principle for the emergence of a constitutively incomplete and unfinished reality. Author Keywords: Bukowski, Concussion, Foucault, Kant, South Park, transcendental

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Format: 2024/03/29